Gasket with a compression limiter

ABSTRACT

A multi-layer gasket including first and second functional layers, each having an opening. Each of the functional layers includes a compression bead, and the compression beads contact and seal against one another when the gasket is compressed between a cylinder head and an engine block. At least one of the functional layers includes a stopper disposed between the compression bead and the opening. The stopper has a gear-like shape including a plurality of circumferentially spaced teeth. Each tooth extends upwardly from a plane by a distance which is less than the combined height of the compression beads. When the gasket is compressed between the cylinder head and engine block, the stopper ensures that the compression beads remain elastically biased against one another and maintain a gas-tight seal.

This divisional application claims priority to U.S. application Ser. No.13/362,459, filed Jan. 13, 2012, and is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to static gaskets of the type used to establish agas-tight seal between two members to be clamped together, and moreparticularly to multi-layer gaskets such as cylinder head gaskets.

2. Related Art

In establishing a gas-tight seal between two members to be clampedtogether, such as a cylinder head and an engine block, it is common touse a static cylinder head gasket having multiple layers. Generally, atleast one of the layers of the multi-layer gasket, sometimes referred toas a functional layer, has a compression bead to establish the fluidtight seal. Another of the layers, sometimes referred to as a distancelayer, is configured to abut the functional layer in an effort toestablish the gas-tight seal by compressing the compression bead of thefunctional layer. Unfortunately, while fastening the cylinder head tothe engine block, the compression bead can be over-compressed andsubstantially flattened. If the compression bead is over-compressed, inaddition to losing its ability to maintain a gas-tight seal, fatiguecracks can form in the area of the compression bead during the initialclamping or while in use. If formed, fatigue cracks ultimately reducethe ability of the static gasket to maintain a gas-tight seal, therebydiminishing the life and performance of the engine.

Some gasket manufacturers have begun producing multi-layer gasketsincluding compression limiters for preventing flattening of thecompression bead when the gasket is compressed between the cylinder headand the engine block. These compression limiters are typicallyadditional components and may either be costly to produce or may fullyprevent flattening of the compression bead.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a multi-layer gasket forestablishing a fluid-tight seal between a first member and a secondmember is provided which includes a compression limiter in the form of astopper for preventing full flattening of a compression bead when thegasket is compressed between the first member, e.g. an engine block, andthe second member, e.g. a cylinder head. The gasket has one or morelayers, and the stopper has a gear-like shape and is integrally formedwith one of the layers through an embossing process. Each tooth of thegear-shaped stopper extends upwardly from a plane by a distance which isless than the height of the compression bead if the gasket has a singlelayer or the combined heights of the compression beads if the gasket hasmultiple layers. Accordingly, both of the compression beads extendupwardly from the plane and remain elastically biased against oneanother, even if the cylinder head is over-loaded onto the engine block.As such, the compression beads are assured of maintaining a generallyconstant, high sealing pressure against one another, thereby providingand maintaining the gas-tight seal about the circumference of thecylinder bore. In addition to maintaining the desired gas-tight sealabout the cylinder bore, the compression beads, by not beingover-compressed and completely flattened, remain free from the formationof premature fatigue cracks both during assembly and while in use. Thus,for very little additional cost, the gasket is protected from fullflattening of the compression bead, even if the cylinder head isover-loaded onto the engine block.

According to another aspect of the invention, the heights, radiallengths, widths, circumferential spacing and/or the directions of theteeth are varied around the opening. By varying any combination of theseparameters, a non-uniform pressure distribution between the compressionbeads around the opening can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bereadily appreciated, as the same becomes better understood by referenceto the following detailed description when considered in connection withthe accompanying drawings wherein:

FIG. 1 is an exploded view of a known gasket positioned between acylinder head and a gasket;

FIG. 2 is a perspective fragmentary view of a known multi-layer gasket;

FIG. 3 is an exploded and fragmentary view of an exemplary multi-layergasket disposed adjacent an engine block;

FIG. 4 is an exploded and fragmentary view of a first embodiment of thegasket;

FIG. 5 is an exploded and fragmentary view of a second embodiment of thegasket;

FIG. 6 is a top and fragmentary view of a second functional layer of athird embodiment of the gasket;

FIG. 7 is a top and fragmentary view of the second functional layer of afourth embodiment of the gasket;

FIG. 8 is a top and fragmentary view of the second functional layer of afifth embodiment of the gasket;

FIG. 9 is a top and fragmentary view of the second functional layer of asixth embodiment of the gasket;

FIG. 10 is a cross-sectional view of a seventh embodiment of the gasket;and

FIG. 11 is a cross-sectional view of an eighth embodiment of the gasket.

DETAILED DESCRIPTION OF THE ENABLING EMBODIMENTS

Referring to the Figures, wherein like numerals indicate correspondingparts throughout the several views, a gasket 20 configured forestablishing a seal between a cylinder head (not shown) and an engineblock 22 is generally indicated in FIG. 3. The exemplary gasket 20includes a plurality of large, generally circular openings 24 whichcorrespond with a plurality of cylinder bores 26 in the engine block 22.The gasket 20 also includes a plurality of holes 28 for allowing boltsor fasteners to extend through the gasket or for allowing coolant toflow between the engine block 22 and the cylinder head, as will beunderstood by those of ordinary skill in the art. Although the exemplarygasket 20 is a cylinder head gasket for use in an internal combustionengine, it should be appreciated that the gasket 20 could be used toseal any desirable members, not just a cylinder head and an engine block22. Additionally, although each of the embodiments shown in the drawingsand discussed below have two layers, it should be appreciated that thegasket could include any desirable number of layers including one layer.

A first embodiment of the gasket 20 is illustrated in FIG. 4. The gasket20 includes a first functional layer 30 and a second functional layer 32overlying one another and secured to one another at their outermostperipheries through, for example, welding, brazing or rivets. Each ofthe functional layers 30, 32 also has an inner periphery 34, 35 definingone of the openings 24 discussed above, as will be understood by thoseof ordinary skill in the art.

Each of the functional layers 30, 32 also includes a compression bead36, 37, a main body portion 40, 41 and an inner periphery portion 42,43. The compression beads 36, 37 are spaced radially from andcircumferentially surround the inner peripheries 34, 35. Each of themain body portions 40, 41 extends along a plane 38, 39, and thecompression beads 36, 37 extend upwardly from the plane 38, 39. Theinner periphery portions 42, 43 extend between the inner peripheries 34,35 and the compression beads 36, 37 and are generally planar with themain body portions 40, 41. The functional layers 30, 32 are preferablyconstructed from a resilient material such as spring steel and can haveany desirable thickness. The compression beads 36, 37 are preferablyformed on the functional layers 36, 37 through an embossing process, aswill be understood by those of skill in the art. As shown in FIG. 4, thefunctional layers 30, 32 are arranged such that the aforementionedcompression beads 36, 37 face one another. Thus, when the gasket 20 iscompressed between the engine block 22 and the cylinder head, thecompression beads 36, 37 engage one another to facilitate a gas-tightseal about the cylinder bore 24, thereby preventing combustion fluids orgasses from escaping the cylinder bore 24 between the cylinder head andthe engine block 22.

In contrast to the first functional layer 30, the second functionallayer 32 also includes a stopper 44 located on the inner peripheryportion 43 between the compression bead 37 and the inner periphery 35for preventing the compression beads 36, 37 from being completelyflattened between the cylinder head and engine block 22, as will bediscussed in further detail below. The stopper 44 circumferentiallysurrounds the opening 24 and has a generally gear-like shape andincluding a plurality of circumferentially spaced teeth 46 extending outof the plane 39 by a distance which is less than the combined heights ofthe compression beads 36, 37. Therefore, the compression beads 36, 37are allowed to contact and seal against one another when the gasket 20is compressed between the cylinder head and the engine block 22.

The stopper 44 is an integral feature of the second functional layer 32and is preferably formed through an embossing process, similar to thecompression bead 36. The shape and curvature of the teeth 46 providethem with great resistance to flattening, and therefore, when the gasket20 is compressed between the cylinder head and the engine block 22, theteeth 46 contact the inner periphery portion 42 of the first functionallayer 30 and hold the two inner periphery portions 42 apart. Thus,neither of the compression beads 36, 37 can be completely flattenedagainst the other. Accordingly, both of the compression beads 36, 37extend upwardly from the plane 38 and remain elastically biased againstone another, even if the cylinder head is over-loaded onto the engineblock 22. As such, the compression beads 36, 37 are assured ofmaintaining a generally constant, high sealing pressure against oneanother, thereby providing and maintaining the gas-tight seal about thecircumference of the cylinder bore 26. In addition to maintaining thedesired gas-tight seal about the cylinder bore 26, the compression beads36, 37, by not being over-compressed and completely flattened, remainfree from the formation of premature fatigue cracks both during assemblyand while in use. Moreover, the stopper 44 itself provides an extralayer of sealing, which further improves the gasket's 20 sealingability, and also functions as a fire dam to limit the exposure of thecompression beads 36, 37 to the combustion fires in the cylinder bore.All of these additional advantages are achieved at a minimal costbecause no additional components are required and the stopper 44 can becheaply and quickly added to the gasket 20 through the embossmentprocess.

In the exemplary gasket 20 of FIG. 4, the teeth 46 have a generallyuniform circumferential spacing from one another and all rise above theplane 39 by a similar height. Additionally, all of the teeth 46 extendradially toward the compression bead 37 by a similar distance. Such astopper 44 might be preferred if a generally uniform sealing pressure isdesired around the circumference of the cylinder bore 26. However, aswill be discussed in further detail below, if desired, each of theseparameters could be varied to provide the gasket 20 with a non-uniformsealing pressure around the cylinder bore 26. For example, it might bedesirable to have a wider spacing between teeth 46 in areas where lesssealing pressure is required and to have a smaller spacing between teeth46 in areas where a greater sealing pressure is required.

Referring now to FIG. 5, a gasket 120 constructed according to anotherembodiment is illustrated. Similar to the gasket 20 described above,this gasket 120 includes first and second functional layers 130, 132,each having a compression bead 136, 137. The second functional layer 132also has a stopper 144 comprising a plurality of teeth 146 disposed inthe inner periphery portion 143. As shown in phantom lines, some of theother teeth 146 rise to different heights above the plane 139 than thetooth 146 through which the cross-section was taken. Teeth 146 havingdifferent heights will impact uniformity of the pressure exerted betweenthe compression beads 136 around the opening 124. Specifically, morepressure will be exerted between the compression beads 136, 137 if theteeth 146 are shorter, whereas less pressure will be exerted between thecompression beads 136, 147 if the teeth 146 are larger.

Referring now to FIG. 6, the second functional layer 232 of a gasket 220constructed according to yet another embodiment is shown. Similar to thegaskets 20, 120 described above, the compression beads 237 extendcircumferentially around each of the openings 224, and the stoppers 244are disposed on the inner periphery portions 242 between the innerperipheries 243 and the compression beads 237. In this embodiment, theteeth 246 of the stopper 244 have varying circumferential spacing,varying widths and they extend radially by different distances towardthe compression beads 237.

The second functional layer 332 of a gasket 320 constructed according toanother embodiment is shown in FIG. 7. In this gasket 320, the teeth 346of the stopper 344 are generally uniformly circumferentially spaced fromone another but extend radially toward the compression beads 337 bydifferent distances from one another. As discussed above, this couldhave an impact on the uniformity of the sealing pressure between thecompression beads 337.

The second functional layer 432 of a gasket 420 constructed according toyet another embodiment is generally shown in FIG. 8. In contrast to thestoppers 44, 144, 244, 344 described above, the teeth 446 of thisstopper 444 extend inwardly toward the opening 424 rather than towardthe compression bead 437. This is yet another example of how the stopper444 can be modified while retaining its ability to prevent flattening ofthe compression beads 437.

The second functional layer 532 of a gasket 520 constructed according toyet another embodiment is illustrated in FIG. 9. This gasket 520 isdistinguished from the gaskets 20, 120, 220, 320, 420 described abovebecause the teeth 546 of the stopper 544 alternate between extendingtoward the opening 524 and extending toward the compression bead 537. Itshould be appreciated that the teeth 546 could take any desirablepattern in order to create a gasket 520 with specific sealingcharacteristics. For example, it might be desirable to have two teeth546 to extend toward the compression bead 537 for every tooth 546extending toward the opening 524.

Referring now to FIG. 10, a gasket 620 constructed according to afurther embodiment is illustrated in cross-section. This embodiment isdistinguished from the gaskets 20, 120, 220, 320, 420, 520 describedabove because both the first and second functional layers 630, 632 havea stopper 644, 645 disposed on their respective inner periphery portions642, 643. Such a gasket 620 could be advantageous because the functionallayers 630, 632 have mirror profiles of one another. In this embodiment,the teeth 646, 647 have a combined height which is less than thecombined height of the compression beads 636, 637 to allow thecompression beads 636, 637 to contact and seal against one another whenthe gasket 620 is compressed between the cylinder head and the engineblock.

Referring now to FIG. 11, still another embodiment of the gasket 720 isillustrated. In this embodiment, the gear teeth 746, 747 of thefunctional layers 730, 732 are interleaved with one another, i.e. thegear teeth of the first functional layer 730 extend radially inwardlytoward the opening 724, and the gear teeth 747 of the second functionallayer 732 extend radially outwardly toward the compression bead 736.Because the teeth 746, 747 are interleaved with one another, each shouldhave a height which is less than the combined height of the compressionbeads 736, 737. Interleaving the teeth 746, 747 could have the effect ofstrengthening the stopper 744 and/or improving its ability to blockcombustion gasses from ever reaching the compression beads 736, 737.

It should be appreciated that the gasket could take many forms otherthan those shown herein. For example, rather than having the compressionbeads facing toward one another, they could face in the same directionand sealed to one another in a nesting relationship. Additionally, thegasket could include any number of functional layers, and could alsoinclude one or more distance layers (not shown), if desired.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings and may be practicedotherwise than as specifically described while within the scope of theappended claims.

What is claimed is:
 1. A multi-layer gasket for establishing afluid-tight seal between a first member and a second member, comprising:a first functional layer having at least one opening and at least onecompression bead, said at least one compression bead projecting out of aplane of said first functional layer and extending circumferentiallyabout and spaced from said at least one opening; a second layeroverlying said first functional layer and having at least one openingthat is aligned with said at least one opening of said first functionallayer; said second layer consisting essentially of at least onecompression bead and an embossed stopper; said at least one compressionbead of said second layer projecting out of a plane of said second layerby a predetermined distance; said embossed stopper surrounding saidaligned openings, said embossed stopper having a stopper bead that iscircular in shape, and said embossed stopper having only a single row ofcircumferentially spaced teeth which extend radially from said secondbead towards said aligned openings; and said second bead and said teethextending out of said plane by a distance that is less than saidpredetermined distance of said at least one compression bead forlimiting compression of said at least one compression bead.
 2. Themulti-layer gasket as set forth in claim 1 wherein said at least onecompression bead of said first functional layer is embossed onto saidfirst functional layer.